1. Field of the Invention
The present invention relates to an exposure method and a method of manufacturing a semiconductor device using the exposure method. In particular, the present invention relates to an exposure method using holography.
2. Description of the Related Art
In recent years, an exposure technique using holography has drawn attention as a pattern formation method in the process of manufacturing a semiconductor device. The exposure technique using holography includes a step of recording a hologram in a medium for the recording of a hologram (hereinafter referred to as a “hologram recording medium”) by illuminating the hologram recording medium with an object beam and a reference beam (a recording step), and a step of reconstructing a holographic image on an illumination target such as a resist by illuminating the hologram recording medium with a reconstruction beam (a reconstruction step).
In the recording step, the hologram recording medium is illuminated with a first laser beam (an object beam) through a mask having a desired pattern, and at the same time, the hologram recording medium is illuminated with a second laser beam (a reference beam) from a direction different from the first laser beam. Thus, by illuminating the hologram recording medium with the first laser beam and the second laser beam at the same time, a fringe pattern that is produced by optical interference between the first laser beam and the second laser beam is formed in the hologram recording medium. In the reconstruction step, the hologram recording medium is illuminated with a laser beam as a reconstruction beam, so that diffraction rays that reproduce the original pattern are projected onto a resist which is formed over a substrate.
Research has been conducted on a micropattern formation method or the like. For example, in the recording step and the reconstruction step of the exposure technique using holography, a resist is formed into a pattern with a smaller feature size than the original pattern by using laser beams which are emitted from different kinds of laser oscillators (for example, see Reference 1: Japanese Published Patent Application No. 2004-253660).